IMS and other devices are being increasingly used to detect trace quantities of substances. For example, at airports and the like, there is commonly a strong demand for detection of explosives, illegal narcotics and other substances. In the past, the lack of suitable machines or devices for detecting such substances has lead to use of trained dogs for detecting them. This has its own disadvantages. Clearly, a dog can only work for a certain length of time and a dog's degree of enthusiasm and interest can vary.
More recently, IMS devices have become available having an extremely high degree of sensitivity, sufficient to detect very low levels of narcotics and the like. They are sufficiently sensitive that even minute quantities of these substances, in the nanogram or picogram range, left on the exterior packages, suitcases etc. can be detected.
However, if the substances are to be detected, there is a fundamental problem of collecting a sample for insertion into an IMS device. A common current technique is to use a small hand-held vacuum cleaner with a teflon filter. This is run over a suitcase or other object of interest. The filter is then removed and inserted into the IMS device and subject to heating leading to vaporization and desorption of vapors of interest.
This technique has numerous disadvantages. It is relatively time consuming and complicated. The vacuum cleaner is noisy and intrusive. In the nature of such an investigation, in a crowded airport for example, it is desirable to be able to gather a sample unobtrusively and discreetly. Further, vacuum samplers require batteries, so they are large and cumbersome.
It requires the filter to be manually removed from the vacuum cleaner and inserted into the IMS device. More significantly, if a "hit" is obtained, i.e. if one of certain substances is detected, then this requires that the various items of equipment used be carefully cleaned. The reason for this is that possibly some trace particles or condensed vapors remain adhered inside the inlet to the vacuum cleaner. If these are not removed, they could become dislodged and then embedded on the filter to give a false positive reading for a later test. It is therefore necessary to carefully clean the vacuum cleaner and other components. This is exceedingly inconvenient, and results in considerable operational delay and inconvenience.
Other techniques have been suggested, but these still have numerous disadvantages. For example, it is known to use a glove, in which case a user's hand is simply run over the suitcase or object of interest. The glove itself is then vacuumed, which is an additional step. Again this leads to the same problem of contamination of the vacuum cleaner if a positive sample is found.
It has been proposed to use a light stainless steel mesh in a holder. While this can be held in a machine, it is too inflexible, and is generally not effective.
Accordingly, it is desirable to provide some method of collecting samples for analysis in an IMS device or the like, which is cheap, simple and effective. Further, the collection technique should not require any significant down time or cleaning to be required if and when a positive indication is found for substances of interest.